Former Soviet Nations, China Face High MDR-TB Prevalence, Study Says
Many countries from the former Soviet Union are facing a high prevalence of multi-drug resistant tuberculosis, and several Chinese provinces also have high rates of the strain, according to a study published online Thursday in the journal Lancet, AFP/Google.com reports.
For the study, researchers examined data collected between 2002 and 2007 on 90,000 patients from 83 countries. They found that of the approximately nine million new TB cases diagnosed each year, about one in nine did not respond to at least one drug. In addition, drug-resistant TB accounts for nearly one-fifth of all TB cases in Eastern Europe, the researchers said. The study found that MDR-TB -- which is resistant to at least two first-line TB drugs -- accounts for between 7% and 22% of all TB cases in nine countries from the former Soviet Union, including 19% of TB cases in Moldova and 22% of TB cases in Azerbaijan's capital of Baku.
In addition, of the more than 500,000 MDR-TB cases reported since 2006, about half occurred in China and India, the study found (AFP/Google.com, 4/15). According to the study, MDR-TB accounts for about 7% of all TB cases in two Chinese provinces, nearly double the average regional rate in Southeast Asia. MDR-TB accounts for about 3% of all TB cases in Latin America and about 2% of all TB cases in Africa, according to the study. In addition, about 1% of TB cases in high-income countries cannot be treated with two or more first-line drugs, the study said. According to the researchers, former Soviet countries and some Chinese provinces "reported the highest prevalence of resistance" to TB drugs worldwide (MacInnis, Reuters, 4/15).
According to the researchers, MDR-TB prevalence has increased in many countries worldwide since the mid-1990s. In South Korea, MDR-TB prevalence increased from 1.6% to 2.7% of all TB cases between 1994 and 2007. In addition, MDR-TB rates in Russia's Tomsk Oblast region more than doubled from 6.5% to 15% of all TB cases during a six-year period. The country's Orel Oblast region also faced an increase in MDR-TB rates, which nearly quadrupled to 8.8% of all TB cases between 2002 and 2006, the study found. MDR-TB rates in Estonia and Latvia remained steady during the 1990s at about 11.3% and 10.8% of all TB cases, respectively, compared with a decline to about 1% of all TB cases in Hong Kong and the U.S. during the same period.
According to the study, countries from the former Soviet Union are "facing a serious and widespread epidemic with the highest prevalence of MDR-TB ever reported in 13 years of global data collection." In addition, the study identified more than 25 cases of extensively drug-resistant TB in five former Soviet countries: Azerbaijan, Estonia, Latvia, Lithuania and Russia. XDR-TB is resistant to the two most potent first-line TB treatments and at least two of the classes of second-line drugs (AFP/Google.com, 4/15). According to health experts, many former Soviet nations faced drug shortages during the Soviet era and immediately following the USSR's collapse, which might account for the region's high prevalence of drug-resistant TB. The researchers said MDR-TB control and prevention will require better tests to identify drug resistance among TB cases and ensure proper medication and treatment (Reuters, 4/15). "Currently, the world is far behind reaching targets for MDR-TB diagnosis and management," the researchers said (AFP/Google.com, 4/15).
An abstract of the study is available online.